Apparatus responsive to accelerations



June 4, 1940. Ei scHME'n-w 72,203,061

APPARATUS RESPONSIVE '1'0 AGGEDERATIONS Filed :my s1. 1938 s sheets-sheet 1 June 4, 1940. s scHME-r'row APPARATUS RESPONSIVE TO AGCELERA'IIONSA Filed lay 31.. 1938 5 Sheets-Shea?l 2 June 4,1940. E. scHMl-:T'row 2,203,061

APPARATUS RESPONSIVE TO ACELERATIQNS Filed uayl, lsa 5 sheets-sheet s June 4, 1940 E.- scHMETrow 2,203,061

unnmms nnsronsxvs 'ro commu-Ions Filed my 31. 193s i s sheets-sheet 4 June 4,'1940. j SCH'MT-row y 2,203,061

Prunus 'Rssronsrvz 'rc Accnnmzons f I Fina any s1, 195s s shuts-sheet s 20 eration responsive device comprising a pair of UNITED STATES PATENT OFFICE APPARATUS RESPONSIVE TO ACCELERATION S Erich Schmettow, Berlin-Staaken, Germany, as-

signor to Siemens ApparateA und Maschinen Gesellschaft mit beschrnkter Haftung, Berlin, Germany, a corporation o f Germany Application May 31, 1938, Serial No. 211,093

In Germany August 29, 1936 6 Claims. (Cl. 264-1) 'I'he invention relates to an apparatus responsive to accelerations. l

An object of the invention is to provide at least two masses serving as elements responsive to V acceleration. i

A furtherobject of the invention consists in Yarranging the ,two masses responsive to accelera--v tion relatively to each other in such a manner thatthe apparatus has a diii'erent sensitivity with respect to two axes perpendicular to each other.

Another object of the invention is to provide a novel acceleration responsive device comprising a pair of masses so mounted and arranged that the sensitivity characteristic of the device isa function of the separate sensitivity characteristics of the respective masses and alsoa function of the combined sensitivity characteristics of both of said masses.

Still another object is to provide a novel accelmental mode of operation of the device. Y

Fig. 8 is a graph of the sensitivity characteristic of the apparatus for accelerations acting in any direction.

Fig. 9 is a graph of a sensitivity characteristic 'of the apparatus for two unequal masses of any magnitude-responsive to acceleration, with the support axis of the apparatus at an angle to the longitudinal axis of the craft.

Fig. 10 is a graph of a sensitivity. characteristic for two masses of any magnitude and of any' ratio of sensitivity in two directions perpendicular to each other. l

Fig. 11 illustrates an embodiment of the invention employing two masses actuating piezo-electric crystals and arranged in certain guide paths to provide pendulums of infinite length; and

Fig. 12 represents the sensitivity characteristics of van arrangement of the masses according to Fig.l11.

For the sake of clearness only a single mass responsive to acceleration is represented in the embodiment shown in Figs. 1 and 1a. The relative arrangement of the two masses responsive to acceleration will be apparent from Fig. 2.

masses so A'mounted and arranged that said masses act separately during one condition of acceleration and operate in unison during another condition of acceleration.

Another object of the invention is to provide means which serve to transmit the adjusting -motion from the apparatus to a control:v device, the element serving to transmit the adjusting motion being coupled in a certain manner with the masses responsive to acceleration.

A still further object of the invention consists in designing the apparatus in such a manner that the effective accelerations may have any direction.

Further objects of the invention will be apparent from the following description taken in connection with the accompanying drawings in which a plurality of embodiments' of the invention are shown by way of example and in which Fig. l shows a side elevational view of the apparatus, partly in section.

Fig. 1a is a perspective View illustrating in more detail the relativearrangemeni; of certain elements of Fig. 1.

Fig. 1b is a view, partly in section, illustrating in more detail the 'relative arrangement of certain other elements of'Fig. 1.

Fig. 2 is a top view of the apparatus.

Fig. 3 is a section trken on line ULi-E11 of masses responsive to acceleration which may have any form, for instance, the parallelepipedic form shown in the embodiment. In this embodiment the two masses responsive to acceleration are pivotally suspended as a pendulum on a common suspension axis provided by a shaft 3 and move therefore in parallel planes. The two masses are each mounted on the suspension axis by two angular supporting arms, 5, S and l, 8 respectively. The suspension axis 3 is rmly mounted in a frame-like support d and is substantially within the plane of the frame.

Each of the two masses responsive to acceleration cooperates with a spring responsive to the forces acting on the mass. A helical spring '.l is provided for the mass l and a helical spring iii for the mass 2. Between the respective mass and the spring cooperating therewith, there is arranged a coupling element, such as the coupling element Il for the mass i and the coupling element I2 for the mass 2. This coupling element 50 greater part of its length which is connected at Fg- 1- v one end by means to be described later with the Fig. 4 is a front elevational view of the appara-` appertaining mass, While the they unthreaded tus. end of the coupling element is mounted as shown Figs. 5, 5a and 6 show details of the apparatus, in Figs. 5, 5a, and 6 taken together with Figs. 1, 1a,

55 partly in section. and 2. Bushings I3 and I4 respectivelyhaving Fig. 7 is a diagram illustrating the funda.'-

In Figs. 1, la, andi 2, i and 2 denote the two illustrated as a rod threaded throughout the bores I5 and I6 respectively and slot-shaped recesses I'I and I8 respectively are provided for each. of the two coupling elements in the frame I. The two control rods are illustrated as having a circular cross-section and the cross-section areas are suflciently small so that they are freely socketed in the respective bores I5 and I6, as is clearly il lustrated in Fig. 5a. Adjacent the freely socketed ends of the two rods are arranged cross pins I9 and 20 respectively which are guided in the corresponding slots I'I and I8 of their bushings and thus prevent the control rods from being rotated about theiriongitudinal axis. The ends of the control rods as stated above are arranged in the bores with such a clearance that under operating conditions they may freely pivot in their sockets. Furthermore, the control rods may be displaced within the bores I5 and i6 in a longitudinal direction.

Both helical springs d and i@ are stressed in -tension and are secured at one end to the frame i and at the other end respectively to the rods ii and i2 intermediate the ends thereof. lThe springs are attached to the trame l with the aid of the bushings i3 and M as seen in Figs. 5, 5a, and 6 and are attached to the rods ii and [I2 by the pairs of nuts 2i and Z2, respectively, so that the forces of tension are applied to the respective rods. The nuts are adjustable on the threaded portion of the control rods so that the tension of the springs may be adjusted by means of these nuts. In this manner the absolute sensitivity of both masses in their response to acceleration may be adjusted in the desired manner.

0n the free end of each rod is arranged a nut 23 and 24 respectively, which is provided with diametrically opposed knife-like supporting .edges such as 25. 'I'hese edges engage correspondingly grooved seats such as 26, which are arranged in members 21 and 28 attached to arms 5 and ll, respectively, 'by means of extensions 5a and la, respectively; Both rods it and i2 freely extend through the enlarged bores formed in the respective members 2l and 28. in this manner both rods II and i2 are coupled in a noval and effective manner for movement by the masses under the inuence of acceleration. At the same time both masses are adjustably connected to the two helical springs S and l0 through the rods ii and i2. Both nuts 23 and 24 are adjustable with the aid of a thread arranged on the respective rods. By means of this device, the respective angular relationship of the masses may be adjusted in the desired manner. The angular relationship of the masses is determined by the angle formed between the line connecting the center of gravity of the masses with the axis of rotation and the vertical plane passing through this axis of rotation.

A particular advantage of this arrangement lies in the fact that both the suspension angle of the masses and the bias of the springs absorbment longitudinally of the device so that theyl can engage one another. With the aid of this coupling device both masses are caused to cooperate wth one another in the case of accelerations occurring in certain directions, the amount of effect of each mass depending upon the size of the mass, its pendulous length and its angular position, the effects produced by both masses being transmitted to the same spring.

The operation of the above-mentioned arrangement will now be explained inl its barest fundamentals by reference to the diagram shown in Fig. 7 and to the curve of sensitivity disclosed in Fig. 8. In Fig. 7, G1 and G2 respectively denote the two masses responsive to acceleration. Both masses are suspended in the form of a pendulum with the aid of the two supporting arms I1 and I2 respectively and are rotatably arranged about the common axis of rotation D (see Fig. 8). The mass G1 cooperates with a spring F1 which absorbs the mass forces and the mass G2 cooperates correspondingly with a similar spring F2. The supporting frame in which thecomplete device is arranged is indicated by its axis A-l in Fig. 8. Between the two masses is provided a coupling device K of the type disclosed above by means of which the two masses may be coupled in the abovementioned manner. As will be seen from the schematical representation both masses are a1'- ranged in symmetrical relation to each other and to the axis rfi-A of the supporting frame. rThe angle which is enclosed between the pendulum axes, which coincide with the theoretical connecting lines of 'the centers of gravity of the masses with the axis of rotation II, is denoted by a.

In Fig. 8 is shown the sensitivity characteristic for the arrangement schematically represented in Fig. 7. By sensitivity characteristic is meant a curve indicating the combined value and direction of the acceleration to which the device is sensitive. In the curves of Figs. a, 9, and 10, the

reciprocal of the acceleration value is plotted, so-

that a great distance represented by a line drawn from the center il to a point on the envelope of the curve remote from t represents that the apparatus is responsive to a very small value of acceleration in the particular direction in which the line is drawn. In Fig. 8, A-A is the axis of the supporting frame and B-B is an axis perpendicular thereto. Furthermore, OG1 is the direction of the pendulum axis for the mass i, GGz the direction of the pendulum axis for the mass 2, e the angle betwen these both directions.

Moreover E1 denotes the sensitivity characteristie determined by G1 alone, Ez the sensitivity characteristic determined by G2 alone, Enz the sensitivity characteristic determined by the sum of the masses Gi-l-Gz, Em the curve of sensitivity determined by the sum of the masses Grt-G1, @M1 the direction of the maximum sensitivity of acceleration for the mass G1, OM: the direction of the maximum sensitivity of acceleration for the mass G2 alone.

For a certain plane in which accelerations are effective, the envelope of the sensitivity characteristic is delineated as follows: From the point I) as a partially dotted curve portion and then as a solid curve portion through A, E1,z, E1, Ez, 132,1, the other point A continuing to the dotted curve portion of E2,1 back to point 0. The individual sensitivity characteristics are obtained from the moment vectors which are effective to produce rotation around the axis of rotation 0,`which vectors in turn are determined by the distance of the center of gravity of the masses from the Aaxis of rotation and by the effective acceleration, if the effective acceleration is resolved into the two components of a tangential and a radial acceleration, the latter being absorbed by the suspension device of the corresponding mass. The4 effective acceleration is an angular function of the corresponding components of acceleration, so that as position curve for the said moment vectors, a 'circle is obtained having the diameter OM1 which corresponds to the mass in question in the direction of the maximum sensitivity of acceleration.

For the apparatus, the range E1 and E2 of the individual characteristics is taken into consideration. The greater range of the sensitivity characteristic of the complete apparatus is obtained from the portion E1,z determined by the sum of the masses G14-G2 and from the portion E2,1 of the curve of sensitivity determined by the sum of the masses G2+ G1. If both axes A-A and B-B are considered as reference axes for which a given ratio of sensitivity is required in the direction of both axes perpendicular to each other, the distance OA measures the sensitivity in the direction of the axis A-A and the distance YOB for the direction coinciding with the axis BB. 'Ihe total curve of sensitivity for the instrument is in this instance symmetrical with respect to the axis B-B. It follows that both masses G1 and G1 are suspended at the same angle with respect to the axis A-A, namely, angles B1 and B2 are equal. mass G1 is equal to the mass G2 and furthermore the distance of the center of gravity of the masses for both masses is of the same magnitude.

So far it hasbeen assumed that the axis A--A of the supporting frame for the masses G1 and G2 is rmly supported with respect to the apparatus. It is, however, preferable to arrange said axis A-A not firmly but rotatably in bearings fixed relatively to the apparatus. The whole apparatus constitutes in this manner, a pendulum which may oscillate in a plane perpendicular to the planes of motion of bothmasses. By this arrangement it is possible to determine the curve of sensitivity of the apparatus not only for a single plane but for all planes passing through the axis A-A. I'he sensitivity characteristic Y which is a curve for a given plane, becomes in this manner a surface of revolution, which is obtained by rotating the generating line about the axis A-A, said generating line being formed by the portion of the curve of sensitivity lying under the axis A-A. The above-described example represents a particular instance for a symmetrical curve of sensitivity and particularly for a special arrangement of thev apparatus. In the above-described embodiment it has been assumed, for instance, that the apparatus is arranged in an aircraft, preferably in a high speed airplane. In that case the apparatus is arranged so that axis A-A of the apparatus coincides with the longitudinal axis ofy the airplane or is parallel to the latter. The axes perpendicular to each other for which a given ratio of sensitivity in the direction of both axes is required, are consequently the longitudinal axis and the vertical axis of the airplane. From the curve of sensitivity shown in Fig. 8, it is seen that the sensitivity in the direction of the longitudinal axis of the airplane is considerably greater than thatl in the direction of the vertical axis. In this case particular desired conditions may be readily fulfilled. As an example, it may be assumed that the apparatus is to oper- Furthermore in this embodiment the` ate in the direction 'of the vertical axis only if particularlyA great accelerations occur in this direction, for instance, if when'landing, the airplane' strikes the earth forcefully.

.The apparatus may, however, be easily designed for the general case in which any ratio of sensitivity may be chosen in two axes arranged perpendicularly to `each other in the case ofany direction of these axes and of any form of the curve of sensitivity. In the embodiment shown in Fig. 9 such an instance is shown diagrammatically. A-A denotes the axis of the supporting frame.

The two masses G1 and Ch are suspended in the .form of a pendulum at an angle B1 and a with respect to the axis A-A. `The angle which is enclosed by both masses is denoted by a. Both masses are different in size but have the same distance from the axis of rotation 0 with respect to their center of gravity. The direction of the respective maximum sensitivity of acceleration of the two masses is again denoted by OMi and CM2 and the angle between both directions by e. It is again assumed that ai given ratio of sensitivity is l required in two given directions perpendicular to each other.y The characteristic of sensitivity of the apparatus is composed of the characteristics of the single masses or of the sum of the masses, ire., oi the portions Em, E1, E2, E2,1. The two. directions perpendicular to each other in which the ratio of sensitivity should have a desired value are then determined by both directions A'- and B-B which are displacedy by an angle fy with respect tothe directions determined by the horizontal axis A-A and the vertical axis B-B. The surface of sensitivity shown in Fig. 9, which surface may be produced by rotating Vthe position curve symmetrical to the axis A'-A' as -a generating line, would correspond in this case to a mounting vof the supporting ring in the axis A'A' provided that A-A indicates 'the direction of the longitudinal axis of the airplane.

In Fig. 10 is shown the characteristic of sensitivity of the apparatus for the case in which two masses G1 and G2 of two different sizes are arranged in the form of a pendulum at the same angle 131 and With respect tothe axis ofthe supporting frame A-A. Both masses enclose the angle a, whereas the angle between the directions of the maximum sensitiveness of acceleration is again determined by e. In this case it is assumed that the axis of rotation of the apparatus lies in the horizontal direction and that agiven radius of sensitivity in both directions perpendicular to each other of a horizontal and a vertical axis is required. The surface of sensitiveness of the instrument is then obtained by rotation of the generating liney consisting of the portions E1,z Er

Ea, E2,1 about the axis A--A which in thisv case coincides with the axis A-A indicated as angularly separated therefrom in Fig. 9.

From the embodiments so far described it re sults'that the characteristic of sensitivity is determined by the angle e between the directions of the maximum sensitivity of acceleration of both masses. 'I'he shape of the position curve for the sensitivity may be chosen in any manner by the selection of the magnitude of both masses, furthermore by the selection of the distance of the center of gravity of the masses on the axis of rotation 0, moreover by the yselection of the angle of the oscillating axes with the bearing axis of the supporting frame. Thus, for' instance, in

the case'of the embodiment shown in Fig. 9 a.. diiferent.suspending angle with respectto the axis A-A would result by rotating me axis A'-A' in the direction of the axis A-A.

In order to mount frame 4 for rotation with respect to the craft, trunnions 3l and 32 in bearings 3Ia and 32a carried by uprigbts Sib and B2b, respectively, mounted on base 33a, are provided as shown in Figs. Ji and 1b. To the frame :t are secured iiange-like parts t3 and 34, (see Figs. 1a and 2) which cooperate with the masses at certain positions thereof so to provide a stop to prevent the two oscillating masses from. exceeding a maximum deiiection. A bracket St. (see Fig. 3) secured to the frame 6 carries an. arm 36 which serves to pivotally support at its the-control device 3l pivotally connected at loto the member 3S which extends as a rod 38a towards the outside through trunnion 32 designed. hollow for that purpose. The member 3S is operated through each of 'the forked levers 3S and 40 pivotally supported at 39s and we, respectively, to the respective arms and coupled lto the control device 3l by pins on said device cooperating respectively with'tne forked ends pivotally connected to the corresponding oscillating mass, the free ends of the levers designed in the form of a fork engaging with. journals arranged. on the steering device The member 3S by means oi rod serves to operate a switching device which is provided for example with a toggle switch. The latter has a lever arrangement El, 42 which rotates about a fixed axis 43-43 and which ls guided with the aid of a roller or a pin 45 in a slide 4t provided on the apparatus frame. The toggle action is attained by two springs 48 and' l connected one end to the fixed/axis t-w and at the other end to the pin 45 as will beseen from. Fig. In Fig. l the toggle lever system of the switcli is' shown in released position. In the set position the common pin 48 of the two toggle `Sievers engages the member 38. To prevent an undesired operation of the switch in the case of great acceleration forces masses 49 and il, (see Fig. 4i responsive to acceleration are provided on the lever 4i which holds the toggle in set position upon the exertion of such forces. of the -member 38 is such that the pin 43 is moved by the member 38 only,7 beyond the tilting point, thereafter the joint is snapped under the action of both springs 4l into its end position as shown in Fig. i.

As already above mentioned the shape of the two masses responsive to acceleration is not decisive nor is the particular mounting of both masses. In Fig. 11 is shown an embodiment in which two masses responsive to acceleration are employed which are not mounted in the form of an ordinary pendulum but are arranged in iixeri guide bearings. The two masses are denoted by 5l and I2 respectively and are arranged in a. common supporting housing .53. The two masses `may, for instance, be designed in the form of cylindrical bodies or as bodies with smooth guide surfaces having, for instance, a square crosssection. The mass i! is arranged in a guide path 54 and the mass B2 in a guide pathie y'whereby a pendulous arrangement of innite length is provided. The freedom of motion lies 'in the directions including the angle e which drections represent at the same time the directions of the maximum sensitiveness of acceleration of both masses. Numerals I6 and 51 denote schematically bodies capable of the piezo-electric efiect. A characteristic of sensitivity corresponding to this arrangement is shown in Fig. 12.

The control motion What is claimed is: l. In an acceleration responsive device, a pair of masses, means pendulously mounting said masses for free oscillation about a chosen axis.

a reciprocable motion transmitting member, and means for transmitting the movement of both of said masses under the -inuence of acceleration to said; member comprising a link pivotally connected to each of said masses respectively, a pivoted member connectedto said reciprocable member, pins on said pivoted member and. forked ends on said pivoted links cooperating with said 2. In an acceleration responsive device, a housing, a shaft mounted within said housing, a pair or masses mounted. for movement about said shaft, biasing means for each of said masses limitlng the movement ot saic masses about said shaft during one condition of acceleration, means securing said masses to operate in unison against the action of one of said biasing means during a second condition oi acceleration, the other ci said biasing means being rendered inoperative during said last-named. condition, a control member, and means responsive to the movement or said masses for actuating said control member.

3. In an acceleration responsive device, a frame member, e supporting member mounted within said trame member, Aa rst Weight sus.- pended from said supportingunember for movement in two directions, yieldabie means opposing the movement oi said first weight in one direction of movement and being inoperative during an opposite direction or movement during one conditioner acceieration, a second Weight suspended from said supporting member for movement in two directions in a plane parallel to the movement oi' said ilrst weight, a second; yieldabie means opposing the movement of said second 'ment during said condition of acceleration, a

control member, and means responsive to the movement of-said weights for actuating said control member during movement of said weights.

ll. In an acceleration responsive device, a frame member, a supporting member mounted within said frame member, a first weight suspended from said supporting member for movement in two directions, yieldable means opposing the movement or said irst weight in one direction oi.' movement and being inoperative during an opposite direction of movement during one condition of acceleration, a second weight suspended from said supporting member for movement in two directions in a plane parallel to the movement vof said first weight, a second yieldable means opposing the movement ot said second weight in one direction of movement and being inoperative during-an opposite direction of movement during said condition of acceleration, means securing said weights to act in unison during a second condition of acceleration, a control member, and means operated by said weights for actuating said control member during movement of Vsaid weights 5. In an acceleration responsive device, a`

pended from said supporting member for movement in two directions in a piane parallel to the movement of said rst weight, a second yieidable means opposing the movement of said second 5 weight in one direction of movement and being inoperative during an opposite direction of movement during said condition of acceleration, means securing said weights to act in unison during a second condition of acceleration, .one of 10" said yieldable means operating to oppose the action of said 'weights when their movement is in one direction during the second condition of acceleration and being rendered inoperative when said weights move in the other direction during 15 said second condition of acceleration, a control member, and means operated by said weights for actuating said control member during movement of said weights.

6. In an acceleration responsive device, a frame member, a supporting member mounted in said frame member, a iirst Weight suspended from said supporting member for relative movement in response to accelerations in one direction,

biasing 'means for opposing the movement of said weight, a second weight suspended from said supporting member for relative movement in response to accelerations in -another direction, av

second biasing means for opposing the movement of said last-named weight, said weights acting separately during one condition of accelerationD means carried by said weights for causing them to operate in unison during a. second condition of acceleration, switch means, and means operated by said weights for actuating said switcio means. l 

